Current technologies utilized for gaseous hydrogen storage are limited by the low volume storage gas density at high pressures including pressures in the range of 5,000 to 10,000 psi. The energy density by volume of a gaseous hydrogen is less than that of a gasoline energy density. Use of hydrogen as an alternate fuel source is limited due to this lower energy density. Cryogenic storage of hydrogen at temperatures of around 20° Kelvin may improve the volumetric energy density compared to gasoline storage. However, production of liquid hydrogen is energy intensive and requires special storage and maintenance considerations to avoid hydrogen boil off.
Chemical storage of hydrogen in a solid form such as in a borohydride allows for hydrogen release when heated or mixed with water. However, formation of solid byproducts and release of hydrogen at very high temperatures, due to high activation barrier or thermodynamic stability, limit the use of such materials. Additionally, typically borohydrides are not able to be rehydrogenated at temperatures and pressures appropriate for on board hydrogen storage after hydrogen release.
There is therefore a need in the art for an improved hydrogen storage material that releases hydrogen at lower temperatures and is able to be rehydrogenated after release of the hydrogen.